X-ray tubes having a rotating anode need sophisticated bearing systems, since the anode disc is turning at a high rotation speed. In advanced X-ray tubes, this bearing system is a fluid metal lubricated system including radial and axial bearings supporting the rotary anode on a shaft.
U.S. Pat. No. 6,064,719 discloses such a rotary anode X-ray tube. The bearing system disclosed therein comprises an axial bearing portion and a radial bearing portion, wherein these bearing portions are connected in such a manner that a symmetry axis of the axial and radial bearing portion can perform a swaying motion about the axis of rotation during rotation of the two bearing members. The axial bearing portion is formed by a ring-shaped disc surrounding the anode shaft. The disc is provided with a bore extending parallel to the disc surface and in which is inserted a pin which is guided through a further bore in the shaft. The central zone of the pin which is situated in the bore in the shaft with a small clearance is round so as to be spherical such that this pin has a finite radius of curvature at said area. This way the disc which is rigidly connected to the pin can be tilted out of a perpendicular position relative to the anode shaft through a small angle in any desirable direction. This movability has positive effects on wear.